Stephen said:
I was wondering, what are the downsides to using a dual-supply op amp in
a single-supply configuration?
Stephen
Really there's no such thing as a single supply op-amp. If they run
off a single supply, they are biased to the half way point, so
in effect they do see a dual supply. Run it off a 12v supply,
and bias it to 6volts, and the opamp sees 6volts on the positive
supply line and -6volts on the negative supply line, relative to
that bias point. This isn't any different from running the opamp
off a -6/+6 power supply, since the opamp will have 12 volts across
it.
One disadvantage of running an op-amp off a single supply is
that the input and output will not be at ground, but at half of
the supply voltage (as a result of the biasing). So there won't
be zero DC volts on those lines (unless you measure in reference
to the bias point), and so DC coupling may be out of the question
depending on applications.
The real thing is that "single supply op-amps" are designed so
the output can go closer to the supply voltage. This is useful
since if you're running it off a single supply, usually that is
a lower voltage than the sum when you've got a bipolar power supply,
12volts versus 24volts. The greater headroom of the "single supply
op-amps" means they work better at those lower voltages.
Michael